Capacity Fading of Lithium-Ion Cells Having Li[Li1/3Ti5/3]O4 (LTO)-Negative Electrodes for the First- and Second-Generation 12 V Lead-Free Batteries

Abstract

Lithium-ion cells consisting of Li[Li1/3Ti5/3]O4 (LTO) and Li[Li0.1Al0.1Mn1.8]O4 (LAMO) or Li[Ni1/2Mn3/2]O4 (LiNiMO) were examined at currents higher than 1 mA cm−2 at room temperature. Capacity fading was observed for both LTO/LAMO and LTO/LiNiMO cells during the continuous charge and discharge at 1, 2, and 4 mA cm−2 when a microporous membrane usually used so far was applied. In order to understand the capacity fading, Li/LAMO and Li/LTO cells together with zero-volt lithium-ion cells consisting of LTO or LAMO were fabricated and examined. Among these cells, the rechargeable capacity of a zero-volt lithium-ion cell of LTO with a microporous membrane faded cycle by cycle, while the other cells did not show such obvious capacity fading. From these results, a possible source of capacity fading was discussed in terms of a mass transport problem due to the “zero-strain” insertion electrode combined with a microporous membrane. A solution of the problem is also given in such a way that a non-woven cloth is substituted for the microporous membrane as a separator in LTO/LAMO and LTO/LiNiMO cells for the first- and second-generation 12 V lead-free batteries, respectively.